Selective terminal α2–3 and α2–6 sialylation of glycosphingolipids with lacto‐series type 1 and 2 chains in human meconium

摘要

>Human meconium was found to contain two kinds of gangliosides with the same carbohydrate sequences belonging to the lacto-series. They were detected by TLC-immunostaining with monoclonal antibodies directed to the NeuAcα2–Gal and Lc₄Cer structures. One of these two gangliosides, a major one, which migrated on TLC to a position below that of standard IV3NeuAcnLc₄Cer from human erythrocytes, reacted with the antibody to NeuAcα2–6Gal. The other minor one, which migrated on TLC to a position corresponding to standard IV3NeuAcnLc₄Cer, was detected with the antibody to Lc₄Cer only when the plate, on which the individual gangliosides were separated, was subjected to prior treatment with Vibrio cholerae sialidase. The structures of the gangliosides, each identified by means of permethylation analysis and enzyme treatment after isolation with antibody monitoring, were shown to be IV6NeuAcnLc₄Cer for the former and IV3NeuAcLc₄Cer for the latter, indicating that the lacto-series type 2 (nLc₄Cer) and 1 (Lc₄Cer) chains are sialylated at different linkages, α2–6 and α2–3, respectively. IV6NeuAcLc₄Cer and IV3NeuAcnLc₄Cer were not detected, even in trace amounts, on TLC-immunostaining with the monoclonal antibodies. The concentrations of IV6NeuAcnLc₄Cer and IV3NeuAcLc₄Cer were 448 and 18 nmol/g dry wt of human meconium.